Crankshaft seal



April 20, 1937. K. E. KYLEN 2,077,761

CRANKSHAFI SEAL Filed July 27, 1935 INVENTOR. Karl Erik Ky-Ie'n isATTORNEY.

Patented Apr. 20, 1937 CRANKSHAFT scan Karl Erik Kyln,- Goteborg,Sweden, assignor to Aktiebclaget Svenska Kullagerfabriken, Gotebox-g,Sweden, acorporation of Sweden Application July 2'1, 1935, Serial No.33,529

x In Germany August 1, 1934 5 Claims.

In 2-stroke motors there is usually an overpressure in the crank casebefore the compression period in the cylinder, as thecrank case is usedfor pre-compresston. In all such motors the 5 crank shaft seals oftencause dimculties, as it is impossible to attain an over-pressure in thecrank case, if the seals are ineffective. Consequently the question ofsealing has always required painstaking attention. A sealing ring isusually applied for this purpose, the said ring being fixed to the shaftwith a close running fit and pressed against the stationary wall of the'crank case by meansof springs. This kind of seal is very frequentlyused, but has, however the disadvantage of being very expensive. Thesliding surfaces as well as the corresponding surfaces" in the .crankcase must have a very fine finish in order to assure"- a reliable seal.Furthermore the running fit of the rotating sealing ring on the shaftmust be as close as possible to prevent a too wide space between sealingring andshafta The object of the invention is therefore to provide acheapseal for. such crank cases. On the v rotating member. 1. e. onthecrank shaft, a ring is provided, the diameter of which is onlyslightly smaller than that of the shoulder of the outer bearing ring.The'seal is consequently formed by the outer bearing ring and the ringmounted on the crank shaft. The space between the parts is only a fewtenths of a millimeter in width.

Depending on the conditions, the ring can be made as'a distance ring tobe placed for instance 1 between the cheek of the crankshaft and theroller sets. It can then be used to fix the roller bearing axially. Itis also possible to mount the ring on the inner race ring of the rollerbearing.

Since seals of thiskind are provided at each.

' shoulder of the outer bearing ring, the efficiency of the seal isfurther improved. Distance rings 40 located between the roller sets andwhich are guided at the "outer raceway of the roller, may also serve assealing rings. The sealing space is in this case provided between thesealing ring and the inner roller raceway. The diameter of tion, theinvention is illustrated as applied to a 50 two cylinder 2-stroke motor.The crank shaft a of the'motor is journaled in three places. There aretwo crank cases I) and c'which have to be sealed against the atmosphereand reciprocally.

The crank shaft isjournaled in multi-row cylin- 5 drical rollerbearings? The bearing I is a fourrow cylindrical roller bearingcomprising two double-row bearings with a common outer ring. Within theadjacent shoulders e of the two outer bearing rings a ring d is mountedon the crank shaft which ring has a slightly smaller outer diameter thanthe inner diameter of the adjacent shoulders e of the outer bearingring. The ring d and the two shoulders e thus cooperate to form theseal. The middle bearing 2 is a double row cylindrical roller bearingwith a single outer ring common to both rows of rollers. This bearing isheld in position by means of two distance sleeves f. The distancesleeves are of slightly smaller diameter than the shoulders'g of theouter bearing ring. The sealing closure will thus be located between theends of the distance sleeves f and the'shoulders a of theouter bearingring. The

bearing 3 is a double-row cylindrical roller'bearing with inner racering. Here the sealing rings h are applied on the inner ring 70. Therings h have a somewhat smaller diameter than the shoulders i of theouter bearing ring. The sealing closure will thus here be locatedbetween the rings h and the shoulders i of the outer ring. In additionto the rings d, f and h' mounted on the shaft, the rings 1 can alsobeutilized as sealing rings between the roller sets and guided by theouter raceway of the rollersn The inner diameter of these rings is thenonly a few tenths of a millimeter greater than that of the innerraceway.The sealing closure will then be located between the ring and the innerraceway of the rollers. It is important that the clearance between thesealing parts he only a few tenths-of a millimeter and locatedsubstantially atthe height of the axes of the rollers, i. e. where thegreater part of the opening is covered by the end surfaces of therollers. Having thus described my invention. I claim and desire tosecure by Letters Patent:

1. A crank shaft seal for internal combustion engines operable withcrank case compression,

characterized thereby that sealing ring or rings 2. A crank shaft sealaccording to claim 1,'

in combination a crank case, a crank shaft and a series of antiirictionrollers interposed between the crank case and the crank shaft, astationary sealing member and a rotatable sealing member locatedlaterally of said rollers, there being a narrow annular space betweenthe said seallngmembers located substantially at the height of the axesof the said rollers at the region where the greater part thereof iscovered by the end surfaces of the rollers.

